JP2002275402A - Ink set for ink jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a set composed of an ink for recording with reduced color bleeding even when recorded on a plain paper. SOLUTION: This ink set for ink jet recording comprises a black ink and a color ink and the black ink and the color ink respectively contain at least water, a colorant and a water-soluble organic solvent. The water-soluble organic solvent contained in the black ink and color ink is different in mutual solubility parameter by >=4. In any of the inks, the water-soluble organic solvent is contained in the second largest amount to the water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording ink set used for an ink jet printer.

[0002]

2. Description of the Related Art Conventionally, as an ink jet recording method, an electrostatic suction method, a method of applying mechanical vibration or displacement to ink using a piezoelectric element, or the like, bubbles are generated by heating ink, and the pressure at that time is reduced. An ink ejection method such as a method of using the same is known. Ink droplets are formed by these ejection methods, and a part or all of them is attached to a recording material such as paper to perform recording. As the ink used for such an ink jet recording method,
A variety of water-soluble dyes or pigments dissolved or dispersed in water or a liquid medium composed of water and a water-soluble organic solvent are known and used.

In order to perform good recording over a long period of time using such an ink, it is necessary that the ink used has appropriate characteristics such as viscosity, surface tension, conductivity, density, etc. In order to prevent clogging at the orifice, conditions such as that no precipitates are generated due to heat or the like and physical property values do not change, and that the recorded image is excellent in water resistance, light resistance, etc., are required. It is. Many proposals have been made to satisfy these conditions.

However, in recent years, demands for recording on plain paper have been increasing more than recording on dedicated ink jet paper due to consideration of cost and environment. With many conventional inks, when recording on plain paper, color bleeding, which occurs when different colors are mixed in adjacent portions, is likely to occur, and as a result, print quality deteriorates.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and provides a set of recording inks that can reduce color bleed even when recording on plain paper. The purpose is to:

[0006]

The present invention is an ink set for ink jet recording comprising a black ink and a color ink, wherein the black ink and the color ink are:
Each contains at least water, a colorant, and a water-soluble organic solvent, and the water-soluble organic solvents contained in the black ink and the color ink have solubility parameters different from each other by 4 or more. This is an ink set for ink jet recording which contains the second largest amount of water after water. Hereinafter, the present invention will be described in detail.

The ink set for ink jet recording according to the present invention comprises a black ink and a color ink.
The black ink and the color ink each contain at least water, a colorant, and a water-soluble organic solvent. The color ink included in the ink set for inkjet recording according to the invention is not particularly limited, and examples thereof include a cyan ink, a magenta ink, and a yellow ink, and do not include a black ink. These color inks may be used alone or in combination of two or more.

Although the water used in the present invention is not particularly limited, it is preferable to use not only tap water but also high-purity water such as ion-exchanged water and distilled water. The content of the water may be determined depending on the type of the colorant and the water-soluble organic solvent, the composition thereof, or desired characteristics of the ink, but is generally from 10 to 97% by weight based on the total weight of the ink. It is preferred that If it is less than 10% by weight, the ink viscosity becomes too high, and it becomes difficult to discharge from the head. If it exceeds 97% by weight, the ink becomes easily dried. More preferably, it is 30 to 95% by weight,
More preferably, it is 40 to 90% by weight.

As the colorant used in the present invention, for example, dyes, pigments and the like can be used. As the dye, a water-soluble dye represented by a direct dye, an acid dye, a basic dye, a reactive dye or the like is used. The water-soluble dye is not particularly limited, but is preferably a dye that is suitable for ink used in an ink jet recording system and satisfies the required performance such as sharpness, water solubility, stability, light resistance, and the like. I. Direct black 17, 1
9, 32, 51, 71, 108, 146, 154, 16
8; I. Direct Blue 6, 22, 25, 71,
86, 90, 106, 199; I. Direct red 1, 4, 17, 28, 83, 227; I. Direct Yellow 12, 24, 26, 86, 98, 132,
142; I. Direct orange 34, 39, 4
4, 46, 60; C.I. I. Direct violet 4
7, 48; I. Direct brown 109;
I. Direct green 59; I. Acid Black 2, 7, 24, 26, 31, 52, 63, 112, 1
18; I. Acid Blue 9, 22, 40, 59,
93, 102, 104, 113, 117, 120, 16
7, 229, 234; I. Acid Red 1, 6,
32, 37, 51, 52, 80, 85, 87, 92, 9
4, 115, 181, 256, 289, 315, 31
7; I. Acid Yellow 11, 17, 23, 2
5, 29, 42, 61, 71; I. Acid Orange 7, 19; C.I. I. Acid violet 49; C.I.
I. Basic black 2; I. Basic blue 1, 3, 5, 7, 9, 24, 25, 26, 28, 29;
C. I. Basic Red 1, 2, 9, 12, 13, 1
4, 37; I. Basic violet 7, 14,
27; I. Food Black 1, 2 and the like.

The pigment is not particularly limited as long as it can be dispersed in an aqueous phase, and examples thereof include azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments; phthalocyanine pigments, perylene, perinone pigments, and anthraquinone Polycyclic pigments such as pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments; dye lakes such as basic dye lakes and acid dye lakes; nitro pigments, nitroso pigments, aniline black daylight Organic pigments such as fluorescent pigments; and inorganic pigments such as titanium oxide, iron oxide pigments, and carbon black pigments. As the pigment used in the present invention, those obtained by subjecting the above various pigments to a surface treatment with a surfactant, a polymer dispersant, or the like can also be used. Such a material includes, for example, graft carbon.

When the above-mentioned pigment is used as a colorant used in the present invention, a dispersion treatment is carried out by a conventionally known method together with a suitable dispersant, a solvent, pure water and, if necessary, other additives. As the dispersant, for example, a polymer dispersant or a surfactant used for dispersing a pigment described in JP-A-62-101672 can be used. The polymer dispersant is not particularly limited,
For example, proteins such as gelatin and albumin; natural gums such as gum arabic and gum tragacanth; glucosides such as saponin; methylcellulose, carboxycellulose,
Cellulose derivatives such as hydroxymethylcellulose; natural polymers such as ligninsulfonate and shellac; polyacrylates, styrene-acrylic acid copolymer salts, vinylnaphthalene-acrylic acid copolymer salts, styrene-maleic acid Salts of polymers, salts of vinyl naphthalene-maleic acid copolymers, sodium salts of β-naphthalene sulfonic acid folimarin condensates, anionic polymers such as phosphates;
Examples include nonionic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyethylene glycol.

Examples of the surfactant include anionic surfactants such as higher alcohol sulfates, liquid fatty oil sulfates, and alkyl allyl sulfonates; polyoxyethylene alkyl ethers and polyoxyethylene alkyl esters. , Nonionic surfactants such as sorbitan alkyl esters and polyoxyethylene sorbitan alkyl esters. These dispersants may be used alone or in combination of two or more. Generally, the amount of the dispersant is preferably 0.01 to 20% by weight based on the total weight of the ink. If the amount is less than 0.01% by weight, effects such as adjustment of surface tension will not be sufficiently exhibited. If the amount exceeds 20% by weight, not only the effect will not be increased but also adverse effects such as an increase in ink viscosity will be caused. is there.

The disperser used for the pigment dispersion treatment is not particularly limited, and a general disperser can be widely used, and examples thereof include a ball mill, a roll mill, and a sand mill. Among them, a high-speed sand mill is preferable. The above dyes and pigments may be used alone, respectively, or two or more dyes and pigments may be used in combination. The content of the coloring agent is generally 0.1 to the total weight of the ink.
Preferably, it is about 20% by weight. When the amount is less than 0.1% by weight, it is difficult to sufficiently develop color on plain paper. When the amount exceeds 20% by weight, precipitation and aggregation of the colorant may occur in the ink. More preferably, 0.
3 to 15% by weight, and more preferably 0.5 to 10% by weight.
% By weight.

The water-soluble organic solvent used in the present invention is not particularly restricted but includes, for example, alkyl alcohols having 1 to 5 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol and n-butyl alcohol; dimethylformamide Amides such as dimethylacetamide; ketones or ketoalcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; alkylene groups having 2 to 6 carbon atoms such as ethylene glycol, propylene glycol, triethylene glycol and diethylene glycol. Glycerin; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol monomethyl (or ethyl) ether;
Diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl)
Lower monoalkyl ethers of polyhydric alcohols such as ethers; triethylene glycol dimethyl (or ethyl)
Lower dialkyl ethers of polyhydric alcohols such as ethers; sulfolane, pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone,
1,5-pentanediol and the like can be mentioned. These may be used alone or in combination of two or more.

[0015] The content of the water-soluble organic solvent is not particularly limited as long as it is contained next to water in any of the inks, and may be in a wide range depending on the composition of the ink or the desired characteristics of the ink. The content may be determined, but it is preferably contained at 3% by weight or more. If the content of the water-soluble organic solvent is less than this, a sufficient effect of suppressing color bleeding when contacting the adjacent ink is not exhibited. More preferably, it is 3 to 40% by weight, still more preferably 5 to 3% by weight.
0% by weight.

The water-soluble organic solvents contained in the black ink and the color ink included in the ink set for ink-jet recording of the present invention are used in combination such that their solubility parameters are different from each other by 4 or more. As used herein, the solubility parameter (δ) is defined as the evaporation energy (Δei) and the molar volume (Δei) of an atom or group of chemical structures.
vi) means a value calculated by the following Fedors calculation formula. [Δ = (ΣΔei / ΣΔvi) ^1/2 ] (Fedors
The solubility parameter is calculated from the chemical composition as described above, and is also measured from the heat of evaporation, from the refractive index, from the Kauributanol value, from the surface tension, etc. It can also be determined from the value.

In general, the solubility parameter is close to each other when the values are close to each other, and the solubility becomes difficult as the value difference increases. If the difference between the numerical values is less than 4, a sufficient effect of suppressing color bleed will not be exhibited. If the value difference is 4 or more, the effect is recognized, but usually, a value having a difference of 4 to 10 is suitably selected. When two or more color inks are included in the ink set for inkjet recording of the present invention, the solubility parameters of the water-soluble organic solvents contained in each color ink may be the same.

Suitable combinations of water-soluble organic solvents include, for example, ethylene glycol (δ = 17.8), 1,3-butanediol (δ = 11.6) and ethylene glycol (δ = 17.8). 2-pyrrolidone (δ = 1
3.1), glycerin (δ = 20.2) and 2-pyrrolidone (δ = 13.1), glycerin (δ = 20.2) and diethylene glycol (δ = 15.0), diethylene glycol (δ = 15.0) ) And diethylene glycol monoethyl ether (δ = 10.9), polypropylene glycol (δ = 10.3) and diethylene glycol (δ = 1
5.0).

The ink contained in the ink set for ink-jet recording of the present invention needs other known various dispersants, surfactants, viscosity modifiers, surface tension regulators, pH regulators, antiseptic and fungicides. May be contained depending on
Further, the ink set for inkjet recording of the present invention,
When used in an ink jet recording method of a type in which a recording liquid is charged, a specific resistance adjuster such as inorganic salts such as lithium chloride, ammonium chloride and sodium chloride may be contained. Further, when the ink set for ink jet recording of the present invention is used in an ink jet system of a type in which ink is ejected by the action of thermal energy, for example, thermal properties such as specific heat, thermal expansion coefficient, and thermal conductivity are used. The value may be adjusted.

The ink set for ink jet recording of the present invention obtained as described above sufficiently solves the problems of the prior art, reduces color bleed in the ink jet system, and enables clear color recording even on plain paper. Can be given.

[0021]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 <Black Ink Composition> I. Direct Black 154 2 parts by weight C.I. I. Direct Black 19 2 parts by weight Ethylene glycol (δ = 17.8) 23 parts by weight Pure water Remaining Total 100 parts by weight <Cyan ink composition> I. Direct Blue 199 2 parts by weight 1,3-butanediol (δ = 11.6) 20 parts by weight Pure water Remaining Total 100 parts by weight

After thoroughly mixing and stirring the above materials,
It was filtered through a 0.8 μm membrane filter and used for recording evaluation. These inks were recorded using MFC-7150C (manufactured by Brother Industries, Ltd.). The recording sample is recorded by combining colors so that two different colors of ink become the text color and the background color, and the bleeding of the boundary surface where the colors are mixed and the discrimination of the characters are evaluated. The characters thus obtained were used as recording samples serving as evaluation criteria. The size of the recorded character is set to 11 using Microsoft Word97, and the MFC-7150
C was recorded using plain paper (Xerox 4200). The difference in solubility parameter for this combination is 6.
3, and a clear image without color bleed was formed in output on plain paper.

Example 2 <Black Ink Composition> I. Direct Black 154 2 parts by weight C.I. I. Direct Black 19 2 parts by weight Ethylene glycol (δ = 17.8) 23 parts by weight Pure water Remaining Total 100 parts by weight <Magenta ink composition> I. Direct Red 80 2 parts by weight 2-pyrrolidone (δ = 13.1) 23 parts by weight Pure water Remaining 100 parts by weight Using the above inks, output was performed on plain paper in the same manner as in Example 1. The difference in solubility parameter for this combination was 4.7, and a clear image without color bleed was formed at the output on plain paper.

Example 3 <Black Ink Composition> I. Direct Black 154 2 parts by weight C.I. I. Direct Black 19 2 parts by weight Glycerin (δ = 20.2) 20 parts by weight Pure water Remaining Total 100 parts by weight <Yellow ink composition> I. Direct Yellow 142 2 parts by weight 2-pyrrolidone (δ = 13.1) 23 parts by weight Pure water Remaining 100 parts by weight Output was performed on plain paper in the same manner as in Example 1 using each of the above inks. The difference in the solubility parameter of this combination was 7.1, and a clear image without color bleed was formed at the output on plain paper. As described above, in each of the examples, almost no bleeding due to color bleed was observed in the ink set for inkjet recording of the present invention.

Comparative Example 1 In Example 1, ethylene glycol (δ = 17.8) 2 used for the black ink
3 parts by weight of 1,3-butanediol (δ = 11.6) 2
An ink was prepared and output in the same manner except that it was replaced by 1 part by weight. The difference between the solubility parameters in this combination was 0, and in the output on plain paper, color bleeding occurred in adjacent portions, resulting in an unclear image.

Comparative Example 2 In Example 2, ethylene glycol (δ = 17.8) 2 used for the black ink was used.
3 parts by weight of diethylene glycol (δ = 15.0) 20
An ink was prepared and output in the same manner except that the weight part was replaced. The difference between the solubility parameters of this combination was 1.9, and in the output on plain paper, color bleeding occurred at adjacent portions, resulting in an unclear image.

Comparative Example 3 The same procedure as in Example 3 was performed except that 23 parts by weight of 2-pyrrolidone (δ = 13.1) used in the yellow ink was replaced with 20 parts by weight of ethylene glycol (δ = 17.8). The ink was created and output. The difference between the solubility parameters of this combination was 2.8, and in the output on plain paper, color bleeding occurred at adjacent portions, resulting in an unclear image.

[0029]

According to the present invention, since it has the above-described structure, it is possible to provide an ink set for ink-jet recording in which color bleed is reduced and clear color recording is possible.

Continuing on the front page (72) Inventor Kazuma Goto 15-1 Naeshiro-cho, Mizuho-ku, Nagoya-shi Inside Brother Industries, Ltd. 72) Inventor Michiko Aoyama 15-1, Naeshiro-cho, Mizuho-ku, Nagoya City Inside Brother Industries, Ltd. (72) Inventor Shunichi 15-1 Naeshiro-cho, Mizuho-ku, Nagoya City Inside Brother Industries, Ltd. 2H086 BA01 BA53 BA55 BA62 4J039 BA04 BA13 BA35 BA37 BC07 BC09 BC12 BC13 BC16 BC31 BC36 BC37 BC39 BC50 BC51 BC60 BE01 BE03 BE04 BE05 BE12 CA03 CA06 EA15 EA16 EA17 EA19 EA42 EA47 GA24

Claims (2)

[Claims] 1. An ink set for ink-jet recording comprising a black ink and a color ink, wherein the black ink and the color ink are at least:
Water, a colorant, and contains a water-soluble organic solvent, the water-soluble organic solvent contained in the black ink and the color ink, the solubility parameter of each other is different by 4 or more, in any ink An ink set for ink-jet recording characterized by being contained next to water. 2. The ink set for ink jet recording according to claim 1, wherein the content of the water-soluble organic solvent in each ink is 3% by weight or more.